I. Field of the Invention
The present invention relates generally to lighting devices. More particularly, the present invention relates to lenses for lights.
II. Description of the Related Art
Light emitting diodes (LEDs) consume considerably less power than incandescent light bulbs, making their use highly desirable. To increase the luminosity of LEDs, lenses are placed in front of them, which focuses the light into a beam that is essentially perpendicular to the LED junction base. Inevitably, light dispersion from the LED is decreased, which limits the use of LEDs to specialized illumination applications.
LEDs are readily available in the market place. Three of the xe2x80x9cstandardxe2x80x9d LEDs are a basic LED, a bright LED and an ultra bright LED. The basic LED has an output level between 1.5 to 10 mcd and a viewing angle from 75 to 100 degrees. The bright LED has an output level between 10 to 50 mcd and a viewing angle from 50 to 75 degrees. The ultra bright LED has an output level between 50 to 2,000 mcd and a viewing angle from 18 to 60 degrees. All of these LEDs are useful for a focused light beam application that ranges from situations where there is no ambient light situations to those in daylight.
Recent developments in LED technology have resulted in the availability of xe2x80x9csuper high intensityxe2x80x9d LEDs. Super high intensity LEDs are commonly used in cluster applications to replace standard xe2x80x9cspotxe2x80x9d lamp applications and traffic warning devices. The output level is between 6,000 to 20,000 mcd and the viewing angle is a very narrow 4 to 8 degrees. Yet, use of this powerful LED is still limited to focused light applications due to its narrow viewing angle design. A significant problem occurs when a LED is used and the viewer is outside the narrow range of its beam of light Intensity drops off precipitously.
Use of devices such as fresnel lenses or reflectors can assist the human eye in detecting light emitted by an LED over wider viewing angles. However, use is still limited to relatively focused light applications designed for viewing directly in front of the LED.
Various attempts have been made to broaden the LED light beam. For example, a self-powered ornamental lighting device is described in U.S. Pat. No. 4,866,580 by Blackerby. This device includes a LED encased within a bulb. This bulb appears to have no particularly special refracting nor diffusing characteristics. In another embodiment, a metal foil reflector is used to reflect light emitted from the LED.
Similarly, German Patent Number 41 20 849 A1 by Sitz describes an ornamental lighting apparatus using an LED and a bulb enclosure having the characteristics of a candle flame. Like Blackerby above, this member also appears to have no particularly special refracting nor diffusing characteristics.
U.S. Pat. No. 4,965,488 by Hili describes a light-source multiplication device having a planer lens with multiple facets. An LED emits light toward the planer lens. Surrounding the LED is a reflector to reflect any laterally emitted light from the LED toward the planer lens. Light beams transmitted by the planer lens are parallel to one another.
An LED lamp including a refractive lens element is described in U.S. Pat. No. 5,174,649 by Oilstone. The lamp includes one or more LEDs that illuminate the refractive lens element, which has hyperboloids and facets, to give the effect of its being fully illuminated. However, the lighting effect from the lens remains in a narrow viewing angle and in front of the LED. Once the viewer out of the viewing angle, the effect will not readily be apparent.
As described in U.S. Pat. No. 5,311,417 issued to Hey, an Illuminative Sucker and Decorative String Thereof comprises a sucker having a sucker cup portion and a back portion formed on a back portion of the sucker cup portion, a lamp socket secured to the back portion of the sucker and a lamp inserted in the lamp socket. Both the lamp socket and the sucker may be made of translucent or transparent materials. The sucker cup portion has a cavity formed in the cup portion to enable it to be adhered to a flat surface. Once the lamp is lit, the lamp projects light beams toward the back portion of the sucker, especially when the lamp is an LED, causing the back portion to glow unidirectionally. As shown and described, the lamp socket is not a lens that refracts or diffuses light, but is provided to contain the lamp and permit the lamp to emit a unidirectional light beam toward the back portion of the sucker. This is further demonstrated by the shade fitted to the sucker so that light emitted from an incandescent bulb is totally projected onto the back portion.
Lemelson, in U.S. Pat. No. 2,949,531, describes an Illuminated Highway Marker. The marker comprises a base having a rigid housing secured thereto and an electric lamp disposed within the housing. Surrounding the housing is a cover of a transparent plastic which is flexible but thick enough to protect the rigid housing from impact. Although the housing is rounded to one hundred eight degrees of the body diameter to form a convex apex, the apex is not hyperbolically-shaped. As a result, light emitted from an LED striking the apex would not refract and diffuse to illuminate the total outside surface of the housing. The cover has the same shape as the housing and is not capable of defocusing and omnidirectionally distributing the light emitted from an LED.
According to its major aspects and broadly stated, the present invention is a light assembly that includes a carrier, a light source carried by the carrier, and a lens system. The lens system further comprises a first lens to refract and diffuse light emitted from the light source and a second lens to defocus and further distribute the light transmitted by the first lens. The light source is preferably a super high intensity LED, which is inserted into a bore formed in the first lens. Light from the LED is refracted by the first lens and diffused by its frosted outer surface. The first lens is itself inserted into a bore formed in the second lens. Light from the first lens is further defocused and diffused by a series of linear lens sections located on the outer surface of the second lens.
The ability to evenly distribute light over the surface of a single LED is a major advantage of the present invention. In order to evenly distribute the light, two lenses work in conjunction with each other to refract, diffuse and distribute light from the source.
Another important advantage of the present invention is the ability of the outer lens to take on an ornamental shape. This advantage allows the present lens assembly to be used in various novelty items, such as candles and jack-o-lanterns. In addition to taking on ornamental shapes, the lens assembly can carry a fluorescent material so that the lens assembly radiates absorbed light.
Other features and their advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings showing the preferred embodiment of the invention.